The present invention relates to a pneumatic tire, more particularly to an arrangement of grooves and blocks formed in the tread shoulder regions capable of improving drainage performance without sacrificing steering stability and uneven wear resistance.
Pneumatic tires having a block-type tread pattern comprising a plurality of blocks formed in the tread portion are widely used. In order to improve the drainage performance of such a pneumatic tire, water existing between the tread surface and road surface has to be smoothly discharged outside the ground contacting patch from the tread edges.
In order to smoothen the discharge of water from the tread edges, a heretofore widely employed technique is to increase the volume of shoulder lateral grooves opened at the tread edges.
This technique however, inevitably decreases the rigidity of shoulder blocks formed in the tread shoulder regions, therefore, there is a problem such that the steering stability and uneven wear resistance are liable to deteriorate.
Thus, the drainage and the blocks rigidity have an antinomic relationship, and it was difficult to achieve both at the same time.